Various devices for aerating lakes as part of a lake restoration program have been proposed, but methods for comparing aeration efficiency of these devices have limitations. For example, the oxygen transfer coefficient, KLa, might be used, but the values depend upon the size of the lake and other factors that are not always adequately specified in the literature. It is shown that comparisons based on aeration efficiency, P, weight of oxygen transferred per horsepower‐hour are superior to K,a values for rating efficiency of aerating devices. Aerating ratings based on values of P, however, must be sub‐classified for four conditions (steady‐state, non‐steady‐state, polluted, non‐polluted). The derivation, advantages, and utility of aeration efficiency is described.